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Cysteine string proteins are associated with chromaffin granules
L H Chamberlain1, J Henry, R D Burgoyne
1Physiological Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom.
The Journal of Biological Chemistry
|August 9, 1996
Summary
Cysteine string proteins (Csps) are localized to chromaffin granule membranes in bovine adrenal cells, not the cytosol. This finding clarifies the subcellular distribution of Csps in these neuroendocrine cells.
Area of Science:
- Cell Biology
- Neuroendocrinology
- Protein Localization
Background:
- Cysteine string proteins (Csps) are involved in synaptic vesicle trafficking.
- The precise subcellular localization of Csps in chromaffin cells was previously unclear.
Purpose of the Study:
- To determine the subcellular distribution of cysteine string proteins (Csps) in bovine adrenal medullary chromaffin cells.
Main Methods:
- Digitonin permeabilization assays
- Subcellular fractionation and sucrose gradient centrifugation
- Immunofluorescence and immunogold labeling techniques
Main Results:
- Cysteine string proteins (Csps) were not found in the cytosolic fraction of chromaffin cells.
- Csps were detected in membrane fractions and co-localized with dopamine beta-hydroxylase, a chromaffin granule marker.
- Immunogold labeling confirmed Csps are specifically associated with chromaffin granule membranes.
Conclusions:
- Cysteine string proteins (Csps) are bona fide chromaffin granule membrane proteins.
- This localization differs from their previously known presence on synaptic vesicles.